1. Field of the Invention
The present invention relates to a heat exchanger suitable for use in vehicles, and, more particularly, to an improved structure of a heat exchanger having a side tank at a side of a heat exchanger body formed with a heat exchanger core and header tanks.
2. Description of the Related Art
A multi-flow type heat exchanger, for example, used as a condenser or as an evaporator for an air conditioner in vehicles, may be equipped with a side tank at a side of a heat exchanger body. An example of a side tank portion of such a heat exchanger is depicted in FIGS. 9 and 10. Heat exchanger 50 is constructed as a stacking type multi-flow heat exchanger, that has heat transfer tubes 51 and fins 52 alternately disposed. Side plate 53 is provided on the outer side of the outermost fin 52. Side tank 54 is provided on the outer side of side plate 53 for forming fluid introduction/discharge paths 71 and 72.
Side tank 54 comprises a first side tank forming plate 55 provided at a side of heat exchanger body 57, and a second side tank forming plate 56 provided at a non-heat exchanger body side. First and second side tank forming plates 55 and 56 are connected to each other for forming side tank 54. In this structure, first side tank forming plate 55 is formed and processed from a single plate. Drawn projecting portions 58, 59, 60 and 61 are provided integrally with first side tank forming plate 55, and are formed by drawing. Drawn projecting portions 58, 59, 60 and 61 project toward heat exchanger body 57 for forming fluid paths communicating between the interior of side tank 54 and the interior of heat exchanger body 57. On second side tank forming plate 56, protruding portions 62 and 63, which protrude in a direction opposite to the first side tank forming plate side, are provided for forming fluid introduction/discharge paths 71 and 72 in side tank 54. Protruding portions 62 and 63 are formed integrally with second side tank forming plate 56, and extend in the longitudinal direction of second side tank forming plate 56.
In order to enlarge the cross-sectional area of fluid introduction/discharge paths 71 and 72, as depicted in FIGS. 11 and 12, protruding portions 64 and 65 also may be formed on first side tank forming plate 55. A pressure loss in a side tank may be reduced by such enlarged fluid introduction/discharge paths.
In the above-described structure, however, drawn projecting portions 58, 59, 60 and 61 are formed on first side tank forming plate 55, and protruding portions 64 and 65 are also formed on first side tank forming plate 55. Therefore, in portions 66 and 67, which are positioned between protruding portions 64 and 65, and near drawn projecting portions 58, 59, 60 and 61, shown in FIG. 11, the total amount of drawing may be great. The great amount of drawing may cause the generation of cracks on portions 66 and 67, or it may cause an extremely thin portion, resulting in a reduction of strength. Such defects are liable to occur, particularly when projecting portions 58, 59, 60 and 61 are formed by drawing. Further, during the formation of protruding portions 62 and 63 on second side tank forming plate 56, similar such defects may also occur.